1. Field of the Invention
The present invention relates to an ink jet printer for printing on a printing sheet by jetting ink.
2. Description of the Related Art
An ink jet printer is provided with an ink jet head. Ink is jetted from the ink jet head. The ink jet head is provided with an ink jet nozzle, a pressure chamber joined with the ink jet nozzle, and an actuator disposed in a position adjacent to the pressure chamber. Capacity of the pressure chamber is reduced when the actuator is driven, and a quantity of ink corresponding to this reduction in capacity is jetted from the ink jet nozzle. The ink jet nozzle, the pressure chamber, and the actuator form a set, and normal ink jet heads are provided with a plurality of these sets.
Extremely viscous ink may adhere to the interior of the ink jet nozzles of the ink jet head. Alternatively, impurities or bubbles that have flowed from an ink tank may be present in the ink jet head. When these occur, the jetting characteristics of the ink are disturbed, and satisfactory printing quality cannot be obtained. A purge process must therefore be executed periodically. Ink is jetted from all the ink jet nozzles during the purge process, and the extremely viscous ink, the impurities, or the bubbles that are present in the ink jet head are thus discharged.
A technique is known wherein, in order to collect ink that was jetted during a purge process, an ink receiving sheet is disposed between an ink jet head and a conveying mechanism for conveying the printing sheet. This technique is taught in Japanese Laid Open Patent Publication 2000-211159, Japanese Laid Open Patent Publication 2003-63033, and Japanese Laid Open Patent Publication 2000-168062.
In these techniques, the ink receiving sheet is capable of moving. During normal usage of the printer, i.e. during normal printing operations, the ink receiving sheet is caused to retreat to a position that is not opposite the ink jet head. When the purge process is performed, the ink receiving sheet is conveyed to a position opposite the ink jet head.
In the techniques taught in Japanese Laid Open Patent Publication 2003-63033 and Japanese Laid Open Patent Publication 2000-168062, the ink receiving sheet is formed from a material that absorbs ink. Consequently, the ink that was jetted during the purge process does not run down from the ink receiving sheet.
In the technique taught in Japanese Laid Open Patent Publication 2000-211159, the ink receiving sheet is provided with a separate ink collecting body. The ink caught by the ink receiving sheet is absorbed by the ink collecting body, and consequently the ink that was jetted during the purge process does not run down from the ink receiving sheet.
Ink absorbing capability is limited in all these techniques, and the component that absorbs the ink must be exchanged frequently. In the techniques of Japanese Laid Open Patent Publication 2003-63033, and Japanese Laid Open Patent Publication 2000-168062, the ink receiving sheet that absorbs the ink must be exchanged frequently. In the technique of Japanese Laid Open Patent Publication 2000-211159, the ink collecting body must be exchanged frequently.
Since exchanging the ink receiving sheet or the ink collecting body is a complex operation, maintenance of the ink jet printer is extremely time-consuming.